Heat sink



FIG. 1 is a perspective view of the top, front and left side of a heat sink showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a exploded view thereof.

A rear elevational view is the same as the front elevational view.

A left elevational view is the same as the right elevational view. 

The ornamental design for a heat sink, as shown and described. 